Lightning-arrester



(No flodeL) T. A. EDISON.

LIGHTNING ARRESTER.

No. 476,988. Patented June 14,1892.

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UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF LLEIVELLYN PARK, NEIV JERSEY.

LlGHTNlNG-ARRESTER.

SPECIFICATION forming part of Letters Patent No. 476,988, dated June 14, 1892.

Application filed August 14, 1891. Serial No. 402,656. (No model.)

To all whom it may concern.-

Be it known that I, THOMAS A. EDIsoN, a citizen of the United States, residing at Llewellyn Park, in the county of Essex and State of New Jersey, have invented a certain new and useful Improvement in Lightning-Arresters, (Case No. 918,) of which the following is a specification.

The present invention relates to means for protecting electrical circuits and instruments from the destructive effect of lightning and abnormally-high-tension currents; and the object is to provide such a device which shall be certain in operation and exceedingly simple and cheap to manufacture, so that it may be readily and economically replaced after it has been once used.

The deviceis illustrated in the accompanying drawings, in which Figure 1 is a diagram showing the general arrangement of the parts. Fig. 2 is a side View, partially in section, of the arrester.

As the lightning-arrester I employa device in the form of a condenser. This consists simply of two sheets of metal foil, preferably about a foot square, separated by a sheet of paraftined paper and coiled into a roll, as incated in Fig. 2.

In Figs. 1 and 2, 1 indicates one of the sheets of foil, and 2 the other sheet, While 3 indicates the insulating-sheet separating and surrounding them. This roll is inserted into a sheet-metal tube or casing at, which can be secured to any suitable support by means of a band 5. The ends of the tube areclosed by water proof material, (indicated at 6,) through which the wires connected to the two foil sheets may pass.

In using the arrester the sheet of foil 1 is connected to the circuit to be protected by a copper or other suitable Wire 7. The other sheet of foil 2 is connected to ground through a long easily-fused Wire 8, preferably a lead wire. When lightning strikes the circuit 9, the high potential at the line side of the arrester will break through the paper sheet separating the sheets of foil and will pass to ground over the fusible Wire 8. Any current that would pass in this way will ordinarily be sufficient to immediately fuse or burn the wire 8, causing a wide break in the ground branch. At the same time the lightning-arrester is rendered useless; but, owing to its cheapness and simplicity, it can be readily replaced.

What I claim is- 1. The combination, with a circuit, of a lightning-arrester which is destroyed by a single use connected thereto, and a fusible Wire in the circuit of said lightning-arrester, said fusible wire being of such conductivity and character that it will be fused by any current that will pass through the lightning-arrester, whereby both the arrester and the fusible wire will be simultaneously destroyed, substantially as described.

2. The combination, with a circuit, of a lightning-arrester which is destroyed by a single use and consisting of sheets of metal foil separated by insulating material, such as paraffined paper, one sheet of the foil being connected to the circuit and another sheet of the foil being connected to ground, said ground connection including easily fused wire, substantially as described.

3. The combination, with a circuit, of a lightning-arrester which is destroyed by a single use and consisting of sheets of metal foil separated by insulating material, such as paraffined paper, one sheet of the foil being connected to the circuit and another sheet of the foil being connected to ground, one of said connections including easily-fused wire, substantially as described.

4. The combination, with a circuit, of a lightning-arrester which is destroyed by a single use and consisting of sheets of metal foil separated by insulating material, such as parafiined paper, a water-tight inclosing case, one sheet of the foil being connected to the circuit and another sheet of the foil being connected to ground, one of said connections including easily-fused wire, substantially as described.

This specification signed and witnessed this 31st day of July, 1891.

THOS. A. EDISON.

Witnesses:

JOHN F. RANDOLPH, FREDERICK Orr. 

